We study certain symmetries that arise when automorphisms S and T defined on a Lebesgue probability space (X, ℱ, μ) satisfy the equation . In an earlier paper [6] it was shown that this puts certain constraints on the spectrum of T. Here we show that it also forces constraints on the spectrum of . In particular, has to have a multiplicity function which only takes even values on the orthogonal complement of the subspace . For S and T ergodic satisfying this equation further constraints arise, which we illustrate with examples. As an application of these results we give a general method for constructing weakly mixing rank one maps T for which has non-simple spectrum.
@article{bwmeta1.element.bwnjournal-article-cmv84i1p185bwm, author = {Geoffrey Goodson}, title = {Conjugacies between ergodic transformations and their inverses}, journal = {Colloquium Mathematicae}, volume = {84/85}, year = {2000}, pages = {185-193}, zbl = {0966.37001}, language = {en}, url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-cmv84i1p185bwm} }
Goodson, Geoffrey. Conjugacies between ergodic transformations and their inverses. Colloquium Mathematicae, Tome 84/85 (2000) pp. 185-193. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-cmv84i1p185bwm/
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